The primary goal of this proposal is to understand how allosteric conformational properties of the most common, type 1 fimbrial adhesin of E. coli defines its role in the pathogenesis of urinary tract infections. FimH is an adhesive subunit of th type 1 fimbriae and is one of the major factors in the ability of E. coli to cause urinary tract infection. We determined that the mannose-binding lectin domain of FimH can assume two conformational states - with a high- and low-affinity towards terminally-exposed mannosyl residues. The conformational shift in FimH is highly dynamic in nature and is the basis of the ability of FimH to mediate shear-enhanced bacterial adhesion. We intend to analyze the conformational switch in FimH in the context of the immune response against the adhesive protein.